1. Define the term excretion, and list the function of
each of the major excretory organs.
• 1 : the act or process of excreting
• 2 : something eliminated by the process of excretion
that is composed chiefly of urine or sweat in mammals.
• It may include products of protein degradation (as urea
or uric acid),
• Is distinguished from waste materials (as feces) that
have merely passed into or through the alimentary canal
without being incorporated into the body proper
• a waste product (as urine, feces, or vomit) eliminated
from an animal body
What is Metabolic Waste ?¿?
• me-tab-o-lism \ma'tab-e-liz-em\ n the sum total of the
chemical reactions that keep an organism alive
METABOLIC WASTE A BY-PRODUCT OF ....
water dehydration synthesis & respiration
carbon dioxide cellular respiration
urea protein metabolism, deamination
• 1. THE PROCESS BY WHICH METABOLIC
WASTES ARE REMOVED FROM THE BODY
IS CALLED EXCRETION.
• 2. METABOLIC WASTES INCLUDE EXCESS
WATER AND SALTS, CARBON DIOXIDE
FROM CELLULAR RESPIRATION,
NITROGENOUS COMPOUNDS FROM THE
BREAKDOWN OF PROTEINS, AND UREA.
THE SKIN, LUNGS, AND KIDNEYS-ALONG
WITH THEIR ASSOCIATED ORGANS-MAKE UP
THE EXCRETORY SYSTEM.
The SKIN excretes excess water and salts, and a small
amount of urea.
The KIDNEYS excrete the Nitrogenous Wastes, the
excretion of Water is necessary to dissolve wastes and
is closely regulated by the Kidneys, the Main Organ of
the Urinary system.
The LUNGS excrete most of the carbon dioxide
• The main organ within the excretory
system is the kidneys.
• We have Two bean-shaped Kidneys, one
on each side of the spinal cord near the
lower back, one behind the Stomach the
other behind the Liver.
• Together, the two kidneys regulate the
Chemical Composition of Blood.
• Two Blood Vessels Enter and Leave each
• The Renal Artery Enters each Kidney and
the Renal Vein Exists each Kidney.
Kidneys Continued more…
• 3. A Third Vessel, the URETER, leaves each Kidney carrying fluid to the
• 4. Waste-laden Blood Enters the Kidney through the Renal Artery. Excess
water, Urea, and other waste products are removed from the blood and are
collected in the URETER. The most common mammalian metabolic waste
is UREA. The Filtered Blood exits through the Renal Vein.
• 5. UREA is a Nitrogenous product made by the Liver. Nitrogenous Wastes
are initially brought to the Liver as AMMONIA, a Chemical Compound of
Nitrogen so Toxic that it could not remain in the body without harming cells.
• 6. The Liver Removes Ammonia from the blood and converts it to the less
harmful substance Urea. The Urea enters the Bloodstream and is then
removed by the Kidneys.
Lungs: The lungs cause the
reaction that provides energy for
your body for cellular activities .
When respiration occurs carbon
dioxide is release from the body .
As the carbon dioxide
accumulates in body cells, it
eventually diffuses out of the
cells & into the bloodstream,
which eventually circulates to the
Skin: The skin itself sweats as
you know , but when you sweat
the skin releases metabolic
wastes water, salts, & urea. After
water diffuses within your body
the begin to go into the sweet
glands And then, when body
temperature rises, the fluid
(sweat) is released from the
gland, travels through the tube
(duct), & reaches the skin
surface through openings called
Urinary System: The urinary
system (pictured here) is composed
of two kidneys, two tubes called
ureters, one urinary bladder, and
another tube called the urethra.
Like the other organs, the urinary
system releases water salts and
urea. The ureters are simply tubes
that carry urine from the kidneys to
the urinary bladder. The bladder
temporarily stores urine. And the
urethra is the tube through which
urine leaves the body.
Identify the major parts of the kidney.
• #1 - the CORTEX.
This layer is jam-packed with lots & lots of
those nephrons that I just mentioned.
We'll get to the specifics on those in just a
Think of the cortex as the filtering layer of
• #2 - the MEDULLA.
The middle layer. Think of it as the
Tubes carrying filtered wastes travel from
the cortex, through the medulla towards
• #3 - the PELVIS.
This is the area where all of the collecting
tubules come together
& connect with the ureter (which is
The ureter transports the wastes (urine) to
the urinary bladder.
Why Do Kidneys Fail
Why do kidneys fail?
Most kidney diseases attack the nephrons,
causing them to lose their filtering
Damage to the nephrons may happen
quickly, often as the result of injury or
Most kidney diseases attack both kidneys
Why do kidneys fail continued…
• The two most common causes of kidney
disease are diabetes and high blood
pressure. If your family has a history of
any kind of kidney problems, you may be
at risk for kidney disease.
Nephron: the working units of the kidney that
remove waste and extra fluids from the
• Located inside kidney
• About 1 million nephrons per kidney
• Filters waste out of body
– Chemical Exchange happens
• Water and wastes leave body
– Also known as urine
Blood filters through the
Capillary network within
Assists with the filtering in
the Bowman’s Capsule
Fluid enters and reabsorbs
Carpeted with microvilli and
stuffed amino acids, salt,
and uric acid
Loop of Henle:
Fluid flows through here,
Makes the turn and returns
while water continues to
to the Distal Tubule
leave through osmosis
More sodium is reclaimed
Coiled and surrounded by
while traveling through here
Where urine Pelvis of
Leads to the flows to the
and Tubular Secretion
The body produces some thing of a different
structure that has to undergo lysis and
-Lysis – destruction of bacteria
-Assimilation – putting the nutrients in the
right tissues in your body
Filtration occurs in
the glomerulus of the
nephron, where plasma
is forced by blood
pressure into the
• Occurs in the renal tubule.
• Water, glucose, amino acids and essential
ions move from the filtrate back into the
blood by passive AND active transport.
The cells in the tubules remove different
ions and molecules and deposit in the fluid
in the tubules.
How does it relate to homeostasis?
Tubular secretion is very important
in maintaining the pH levels of the
Name the main parts of the
Structure: the kidneys are two
located near the vertebral
column in your
lower back. The left kidney
lies a little higher
than the right kidney.
Function: To separate
urea, mineral salts,
toxins, and other
waste products from
the blood. They
salts, and electrolytes.
Structure: The tubes
leading from the
kidneys to the
Function: Urine flows down partly by gravity,
but mainly by waves of contractions which
pass several times per minute through the
muscle layers of the urethral walls.
Function: Each ureter enters the bladder
through a tunnel in the bladder wall, which is
angled to prevent the urine from running
back into the ureter when the bladder
bladder is a
organ that lies in
Function: The bladder's main function is to
store and release urine. The feeling to
urinate increase as your bladder increases.
When that happens, the nerves from the
bladder tell the brain to empty out because
of the body
Function: The urethra is a tube that
conveys urine from the urinary bladder to
the outside of the body.
• Waste Filtration System
• Waste Removal
• Poison Filtration
• Excretion is the getting filtering out of any
waste products in your body.
• The skin, lungs and kidneys make up the
• Metabolic waste is the aftermath of any
given product, such as water.
• Nephrons- Filters water and wastes into
urine. They are also located outside the
• The main parts of the kidney are the
CORTEX, MEDULLA and PELVIS.
• Re-absorption is when bacteria is killed
and nutrients are absorbed in the right
• Filtration is when plasma is forced into the
glomurulus capsule by blood pressure.
• Kidneys separate different minerals, urea,
and different toxins.
• Ureters are tubes leasing from the kidneys
to the bladder. Urine flows through them.
• Bladder is a hollow organ which holds the
urine. It is located in the pelvis.
• Urethra is the tube leading from the
bladder to the exterior of the body.